English Heritage says that anything is possible in retrofitting heritage buildings, as long as it doesn't leave a permanent scar. So why are engineers still so reluctant to take these projects on?
Retrofitted heritage buildings are considered portfolio trophy-pieces for most architects, but for contractors and engineers there is still stigma attached to what they believe to be unnecessarily complex commissions. It's true that undertaking a heritage retrofit can be a formidable task, particularly when considering the integration of renewable energy sources, but should contractors approach listed building projects with such caution, or view them as a worthy challenge?
"Heritage retrofitting is about thinking outside the box, and unfortunately engineers tend to have a well trodden approach to how they do things," says Geraldine O'Farrell, senior building services engineer at English Heritage. With a new build, each floor and system can be repeated in a formulaic fashion, but retrofitting an existing shell with existing complex systems can often seem like a daunting challenge with unjustifiable costs and planning.
Conservation organisations such as English Heritage and the National Trust are often characterised as the ogres of the planning world, resistant to investors who are interested in giving an old building a new lease of life. "It's actually the reverse," says O'Farrell "We're here to help. We want heritage buildings to be occupied, because if they're not they will be neglected and fall into ruin."
A heritage retrofit is also viewed as a loss-maker because more time and planning is required to avoid damaging historic fabric, but Andrew More, senior building services manager at English Heritage, insists that heritage projects are driving innovation in the field of electrical engineering. "It does involve more research, more surveying and more understanding of what has been done before," he says. "But we know of a project that has used original 1870 cast-iron grill fittings and air ducts as pathways for modern telecoms wiring."
Not all heritage buildings are restricted by a formidable list of guidelines either. The majority contain only a few select historical features that need to be protected, such as a reception area or the outer fabric, leaving the rest of the building open to structural redevelopment.
O'Farrell believes it is prudent to conserve the technical history as well as the architectural to ensure the electrical and civil engineering methods of the past are not lost forever. She says: "It is especially important to preserve the technical history of the Victorian era, during the dawn of lighting and heating systems." Some systems are still functioning after 150 years or more, meaning economically it doesn't make sense to replace them with modern systems that have a considerably shorter lifespan.
Old with the new
Original systems can sometimes fall short of a tenant's modern-day heating expectations, but O'Farrell says installing new building management systems, pumps and modern boilers where necessary can allow the existing systems to function for another century or more.
"We are not anti-modern technology, far from it," says O'Farrell. "In lighting, for example, I will encourage contractors to use up-to-date fittings and techniques. Be bold, put in the latest LED-track lighting, as it's actually more minimalist so avoids hiding some of the building's original features."
Part of the success of a retrofit project is finding the right specialist to integrate the new technologies with the old. Five years ago the Sefton Park Palmhouse in Liverpool was in ruin after years of neglect, reduced to an empty shell of smashed windows, abandoned systems and peeling paint. In 2009 a '5m cash injection from the Heritage Lottery restored the tropical palm house to its former glory.
English Heritage convinced Liverpool City Council to keep the perimeter pipe-work to heat the glass house, commissioning a local marine engineer to build a bespoke, epoxy-sealed steel system that now fits flush inside the original cast-iron pipework.
English Heritage acknowledges and recognises the negative impact of climate change as heritage buildings tend to decay much more rapidly in an altered climate than their modern equivalents. Therefore conserving heat, using alternative means of generating energy and keeping carbon emissions to a minimum are all major concerns of the organisation, and unsurprisingly they believe a good starting point is in regenerating existing buildings.
Richard Cass, CABE Commissioner and partner of Cass Associates, an architect firm concerned with sustainable development (see 'Industry Insider', p57) agrees: "Inherently, if you recycle and reuse a structure it will be far more effective from a sustainability point of view than knocking it down and adding extra waste, building, energy and transport resources to the mix."
However, integrating new energy sources into heritage buildings is often an issue contractors are hesitant to approach. Renewables such as photovoltaics (PV) and wind turbines are seen as a grey area, and the perception is that conservation organisations are unlikely to condone the installation of solar panels protruding from the eaves of protected buildings.
Contrary to popular belief, conservation organisations actually encourage the integration of renewable energy sources into listed buildings, as long as lateral thinking is applied in regards to their positioning. "We discourage people from removing the historical fabric such as roof tiles or slate to install solar panels, as authentic replacements can't always be found," says Caroline Cattini, energy manager at English Heritage. "It's a better idea to place them in the valleys of roofs, on flat roofs, or entirely away from the building."
Sunny side up
O'Farrell says there are a handful'of Grade I listed churches and one cathedral in the UK that are placing PV onto roofs and parapets, which English Heritage fully supports. "If you can't physically see it on a main elevation from the ground, or as long as you can remove it from the building at a later date with no scar, integrating them is not a problem."
One building contributing to the Church of England's projected 42 per cent carbon emission reduction is Bradford Cathedral. Last year it became the first cathedral in the country to generate its own electricity via PV panels. "The panels are laid on top of stainless steel sheets that were put on the south roof in 1993," says Canon Andrew Williams, also the leader of the Cathedral's Eco Group. "The panels are clamped on very carefully and will be able to stand up to extremely strong winds. Nobody can see the roof from ground level, there's been a big fuss about that."
Some PV companies offer individual slate-sized panels that integrate seamlessly into existing roof arrays, but in most cases larger panels must sit flush over the roof covering 30' on the south-west facing side to achieve optimum efficiency. If this position cannot be achieved out of plain view, or the efficiency is likely to be decreased due to shading, English Heritage recommends the panels should be installed away from the building on the ground.
Project managers must also consider the equipment that accompanies PV and turbines, a suitable area must be made available for storage batteries if required and for the inverter, which can be prone to vibration. PV panels and wind turbines may have an operational life of only 20-25 years, so English Heritage recommends mounting panels to the building on a wooden frame or, in the case of turbines, a pole, enabling easy replacement. Wind turbines should be attached to the gable end of a building, but should never be attached to chimney stacks as they are often structurally unstable.
There is some concern about the potential negative effects of wind turbines on wild animals - protected birds and bats in particular - that make historic buildings their homes. If a dense'population of bats is nesting in a historic building, proposed turbines may need'to be'installed further away.
"Local planning authorities do show a lack of knowledge of the product options available, which can delay planning proposals," says Charlotte Webster, public relations manager at PV specialist Solar Century. Solar Century integrated single PV roof slates into a heritage building in Chester after an initial proposal to fit larger panels over the roof covering was turned down.
"We have seen increasing instances of planning authorities saying 'yes' when presented with a portfolio of different PV options to choose from," she says, "this is where the innovation in the industry is going. Planners do need to meet and speak to local installers who will have access to a range of solutions to show them before they can make an informed decision on a particular project."
Routine maintenance on attachments to deteriorating historic fabric must also be carefully considered and the fabric continuously preserved, but this will not prevent major structural redevelopment on aspects of the building that are not protected. "Conservation organisations are not just there to protect historic fabric," says Cass. "They have a very strong preference for seeing old buildings doing something useful, and as long as alterations are done sensibly they are very supportive." *